Method of shaping bimetallic articles



Aug. 19, 1952 s. K. WELLMAN 2,607,246

METHOD OF SHAPING BIMETALLIC ARTICLES I Filed Sept. 21, 1944 5 Sheets-Sheet 1 Jgmae/ K [Ia/(nan ATTOE/VEY Aug. 19, 1952 s. K. WELLMAN METHOD OF SHAPING BIMETALLIC ARTICLES 5 Sheets-Sheet 2 Filed Sept. 21, 1944 //vvewro e 7 Jazz: ac! A? 1%: due

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A TEE/V5) A g- 1952 s. K. WELLMAN METHOD OF SHAPING BIMETALLIC ARTICLES 5 Sheets-Sheet 3 Filed Sept. 21, 1944 A r roe/vex Aug. 19, 1952 s. K. WELLMAN 2,607,246

METHOD OF SHAPING BIMETALLIC ARTICLES Filed Sept. 21, 1944 5 Sheets-Sheet 4 Arrae/ve-K A 8 1.952 s. K. WELLMAN I 2,607,246

METHOD OF SHAPING BIMETALLIC ARTICLES c) flo Patented Aug. 19, 1952 METHOD OF SHAPINGi-BIMETALLIC 7 ARTICLES Samuel K, Wenma Cleveland Heights, Ohio,

w I K. Wellm-an Company, Cleveland,- Ohio, a corporation of Ohio assignor to The S.

. lica io Se e b r 21,

graphite, and then heating the jbfi uette 5o formed to a sintering temperature. Since the sintered metalisrather 'porous and of low tensjile' strength it is desirable to provide a reinforcing'member or backing of stronger metal", and this is accomplished by conducting the hea-ting or sintering step with the briquette held against a properly prepared surfaceof a backing member; The heat of the sintering step causes the pressed powder to sinter together and to integrally bond to the backing member thus forming a bimetallic article having a s'intered metal facing layer integrally bonded to the face of a solid metal backing member. The term sintered metal facing is used to refer to facings produced 19.44, Serial No. 555,116

' density. However, it is frequentlyjdesirablejto by pressing and sintering a predominately metallic mixture of metallic and non-metallic powders.

-Bimetallic articles of this type have found extensive use as rubbing surfaces in heavy-duty applications, as for example, friction members for clutches and brakes and bearings for shafts A typical mixture of powders comprisesz.

arts by weight of about 11 tons per squareinch'and assembled on a prepared-steel backing- ,member and heated to a temperature of about 1450 F. under a pres- .sure of about .100 pounds per square inch. ,The

steel backing member may be of S. A. E. 1030 composition and mustbe suitably prepared'before 'thehe'ating operation. One method of preparation is disclosed in Swartz Patent No.--Re. 22,282.

'The necessity of pressing thepowder to form the briquette and of pressing the briquette 'against the backing during the sinte'ring -and bonding step limits the process, as a practical matter, to the production of articles of vflat .configuration since it is diificult to press the powder to a. curved shape and avoid uneven pressureand produce bimetallic articles of curved form so that they can be used for shaft bearings for for brake shoes adapted to engage a cylindrical or conical surface. Thus, it is customary to shape or bend a hat b metallic strip to curved shape byuse of a bending pressand suitable dies. If the flat bimetallic strip is to be bent so that the sintered taping will be disposed on the inside of the curved strip, there isflrelatiyely little difficulty in' accomplishing' thisjinlaj press using a suitably shaped die. However,"attempts to use a press and die to'bend the bimetallic article so that the sintered facing isldisposed on the outsideof the curve or onthe' convex face of the backing member for use in an internal expanding brake, for example, have not been very successful. The sintered facing of an article so bent is deeply cracked, due probably to the low tensile strength of the sintered layer.

Other and more satisfactory methods for bending such articles to a shape having the sintered facing disposed on the outside have been developed and one such method is described in *Wellman Patent No, 2,289,311, issuedJulyfi, 1942. According to this patent, the fiat bimetallic article is provided with a thin sheetmetal reinforcing member which is integrally bonded to the sintered'iaci'ng forming in'effect a sandwich with the 'sintered material disposed between the thin sheetmetal facing and the thicker solid metal backing memberL; When such a sandwich article is bent inapress, the thin sheet metal facing stretches a'nd' ho'lds the sintered layer together,

minimizingthe cracking of the sintered layer. After being bent, the thin metal facing is stripped orpeeled offleaving a sintered face that is sub-'- stantially free from cracks. This process, of course, is rather time consuming and expensive.

9 An'i'mprov-ed processfor bending such bimetal-' lic articles to curved formation is disclosed in copending applications S. N.7-,429, filed'October 23,1943, of Francis J. Lowey, now Patent No.

2,446,892, granted August 10, 1948, and SFN. 520,162, filed January 29, 11944, of TCharles- H. Tower and Francis J. Lowey, nowuPatent No.

2,446,891, :gr'anted August 10, 19.48. These applicationsteach that the bending of a flatqbimetallic article may besuccessfully accomplished by controlled directional working of the sintered metal facing. Preferably, this is accomplished by passing the bimetallic ,article between, a pair -ofiopposed pressure rolls, in order to compress I and elongate the sintered facing. This elongationtof t e a in r su t t o ed b nd ns the {bimetallic article.

meme

The bending of the bimetallic blank is apparently due to the fact that the sintered facing is enlongated, while the less plastic backing member of steel is not elongated to any appreciable extent. This elongation of one layer only of a bimetallic article in which the two layers are firmly united obviously results in bending of the article. Thus, in a bimetallic blank having a sintered facing composed predominantly of copper bonded to a solid steel backing meniber, the progressive mechanical working will result in considerable elongation of the sintered facing without elongating the backing and a con:

sequent bending of the blank to curved shape with the sintered facing disposed on the outerv or convex side of the backing.

The terms plastic and plasticity may be used to indicate the flowable or deformable properties variations in the degree of bending. My invention comprises the discovery that the effect of 2 such variations may be avoided if the rolls are iirged toward one another under a constant and predetermined pressure and the spacing apart of the rolls is merely controlled by the thickness and density of the blank.

The underlying theory of the operation is not too clearly understood but, as indicated above,

of the sintered material which permit the elongation and cause the bending. While sintered metallic material is generally .of low tensile strength in comparison with solid metal, such as steel, it does possess the property of being plastic or flowable to a rather high degree. In thisrespect, it may be said that it is of high ductility in that it is capable of being deformed and hammered out. 7

'The method of bending may be described as beingaccomplished by applying pressure to laterally extending areas of the article successively I believe that the progressive mechanical working of successive lateral areas of the sintered facing of the bimetallic blank results in controlled and progressive'elongation of the areas and the resultant bending of the blank. If the blank is longitudinally of varying plasticity due It may be practiced on bimetallic articles in which both layers are of solid metal or on articles in which a sintered metal facing of relatively low plasticity, such as an iron-base mixture, is bonded to a backing member of higher plasticity, such as copper. In all of these cases, controlled directional working of the bimetallic article will cause it to assume a curved shape with the more plastic layer disposed on the outer or convex side of the backing. In the case where a sintered iron-base mix is secured to a backing member of copper, the bending will be in reverse direction and the sintered layer will be disposed on the inner or concave side of the backing. The bend- .ing of these latter articles by this method is not ofma'jor importance since it is relatively easy crease the strength of the article.

The copending applications referred to generally disclose the controlled bending of bimetallic blanks, but they contemplate the use of pressure rolls which are rigidly held in the desired position, so as to have a constant spacing apart of to variations in density and/or thickness, the use of constant pressure, according to my invention, apparently serves to greatly reduce or eliminatel theieifectof such variations. It appears that this constant pressure serves to insure that successive lateral areas are subjected to the same degree or amount of mechanical working and thus elongate longitudinally to the same degree.

It is an object of the invention to, provide a new and improved "method by which bimetallic articles having layers of different plasticity may be accurately and rapidly bent, curved, or otherwise formed to the desired shape.

It is a further object of the invention to provide a new and improved method by which bimetallic articles of the type having a sintered metal fac ing bonded to a less plastic backing member of solid metal may be formed to a curved shape of predetermined configuration without injuring or cracking the facing and with the sintered facing disposed on the outer or convex surface of the backing member.

.Other and further objects and advantages of my invention will be apparent from the following cordance with the teachings of my invention;

Fig. 5 is a side elevation of a jig which may be used to form the blank of Fig. 1;

" Fig. 6 is a vertical section on line 6-6 of Fig. 5; Fig.7 is a plan view, on a reduced scale, of an arcuate, flat bimetallic blank suitable for forming articles of conical configuration;

Fig. 8 is a side elevation of the blank of Fig. 7; Fig. 9.is a vertical section on line 9-9 of Fig. 8; -F ig. 10 is a side elevation of the blank of Figs.

7 to Qafter it-has been formed to conical shape in accordance with the teachings of my invention;

Fig. 11 is a vertical section on line H-|l of Fig. 10;

12 is a side elevation of a suitable .jig which may be used in shapingthe blank of Figs.

13 is la'verticalsectionfon line 13%|: of

" Fig. '14: is aidiagrammatical: showing of-"apparatus suitable for shaping the blank of Figs.

Fig. 15 is a diagrammatical illustration similar to thatshownin Fig. 14, but illustrating theuse ofthe'jig of Figs. '5 and 6; Fig. 16 is a front elevation of suitableapparatus for'carrying out the invention; a

"Fig; 17 is a vertical section on line l'l--ll= of FigJlGbiit on an enlarged scale. s

' Fig; 18 is-a -horizontal section on Fig.17; "'Figrlil 'isa front elevation of the apparatus of Fig.1? with parts broken away and parts in sec- I 20-is a side elevation correspondingto Fig. '17 but showing a modified form of pressure-apfilyineap r '21 is -;a 'horizontalsection online 2 l---'2.l of

" Figfi2'2fisa-vertical elevation'on line -2-2 -'-'22- of thelftf side'bf the'apparatus of Fig. 20. v Bymy invention I propose to take the flat blank 1 show'n'j'in Figs. 1 to 3 and-bend-it toa curved formationas-"shown in- 4-with the sintered facing 3==disposed on'the outeror convex face of thesteel backing member 2;- This I accomplish by passing the bimetallicblank I between'a pair of opposed pressure rolls. 'Thus, referring to Fig. 1'4, which diagrammatically illustrates the bendingopera'tiom the bimetallic blank I is shown in position between a-pair of opposed pressure rolls 6 and 'l. In this figure, the-blank -l is shown as traveling 'fromthe'leftf-to the right-of the figure. *I'hfiotted lines show-theposition of the blank at it'smid-point in-its first-pass between the rolls and' with the right side of the blank partially curved. In its solid-lineposition, the partially curvedblanlr is shownin its second'pass between the rolls and the right side of the blank is shown as having achieved the final-and desired'curvature. Inth'is figure,"the pressurerolls 6 and I are "shown provided with backing rolls'8 and 9 which serve to hold .thepressure rolls -6 and 1 in place antrto-rotate them. I

is disclosed in the said copending applicajtions'above'referred to,lthe degreeof curvature "achieved will be 'dep'endentupon the relative densitmthickness, and plasticity of the facing 2 and fthefbacking' 3;therelative thickness of these'two p'a'fts 'ahd the speed, idiameter. and pressure apjpu iijbythe'rolls, The progressive mechanical working achievedbythe rolls 'G'and-I causes the -less dense'facing layer-to be compressed and elong'a'ted resulting in curvature of I the'blank. "While there are many factors aifectingthebending op- 'eratiomthe major'item'controllingthe extent of bending is thegxtentof mechanicalworki'ng by 'the; rolls. j This in turn is dependent on the density and,thit'zk'ness of the facing and the amount of ipressure'jappliedto the rolls. For anyxgiv'enbifmeta'llicfarticle, the degree of bending is proportional to thedegree of 'working andthus-bending to asmaller radius merely requires the use 'of a igreaterfp'ressure on thef'pressure rolls-t0 obtain ."a-gifeater elongation ofthe sintered'facing. This mechanical working obviously results in a slight .decreasein thickness of the'facing layer, butthis 'iianeasilybe accommodated for by using an ini- 1e '15 illustrates .the', operation of thejpressure ally thicker article than 'thatdesired aftertbend- "ibiist and '1 when used in conjunction with a'ji 6. l l. The-operation is essentially thesanie asthat shown in 14 but the jig l [serves-to limit and control the bending of thebimetallic'blank: l This jig 'll-is illustrated in Figs. 5 and -6.' and- 1s shown as-com'prising a strong, solid metalcylindrical m'ember' l2, preferably of steel, towhich are welded'tabs or lugs l3'which cooperate with the member l2 to definea partialchannel forreception of the bimetallic blank. The lugs can be omitted or could be continuous; if desired; to form a complete. channel. Obviously, the cylindrical member 12 has an outer surface whose radius of curvature is substantially equalatothe inside radiusof the-desired curvature of the back ing member '2 of the bimetallic blank-I.

The invention is'applicable tothe formation of conical shapes as well as the cylindrical shape-of Fig.4. Thusg the-arcuate fiat segment [6 or Figs. '7, 8, and 9 having the steel-backing t8 andsintered facing 1 integrally bonded thereto may. be formed tofthe-conical shape shown in Figs.-.,l0' and 11. by

passingth'esame between thepressure rolls .6 and l. The conical shapeis achieved by a-djusting the pressure-applying means of the rollsso thatthe pressure appliedby the rollslincreasesin amount across-the segment, the area generally included-by the-bracket A of Figs. 7, 9; and. 11 receiving the greater pressure. This-greater pressureresults in greater working of that portion oftthezfacing and consequent greater degreel-of bending. Figs. 12 and 13 illustrate a conical jig .2l' corre: spondingto'the cylindrical jig ll of Figs. .5 andi'6 but for :use with the arcuate segment. [6 of Fig.

-Thisjig 2| has a conical .steellmember. 22 to which :are'weldedspaced side lugs 23 to define a partial channel for receptioniof the blank 1:6. Thus, if this jig 2| and the bimetallicblank rlfiaare passed between the'pressure rolls 6 and I asshown i'n'Fig. 15, theblankwillbeformed to a conical shapeif the rolls are urged toward each other with a pressure that increases along:thelength of the rolls. This will be further'dealt with below. l

Referring nowto Figs. 16 through'lQ, I. have illustrated one suitable form :of apparatus-for achieving the abovedesired results. Fig. 16 gen.- erally shows the apparatus as comprising a base 3| on'which is located the roll unit generallyjindie cated at 32. Disposed withinthebase "31 isa motor '33 which drives .a gear reduction unit 34 through a belt 36. Thegear reduction unitf34 is coupled to the backing and drive rolls,8 and 9. of

The roll .unit .32: comprisesside frames'39 andjl whichsupport thebearing blocksxfor' the backing rolls.8 andandthepressure rolls 6 and 1.. All of thegrolls areimounte'dfor vertical movement, the lower "rolls being adjusted by means .lofifthe handwheel 42 and the upperv rolls by means of .a

pressure applyingsystem 43; all 'as will be described in greater :detail hereinafter.-

As-shown-in'Fig. 17;the side frame 39 comprises a lower-base member 44 which is bolted at Extending upwardly from the vertical shoulders 49 and 5| which cooperate-to form a guide or slideway 50. A thickplate 52- spans the upper ends of the side members and 48 and is bolted thereto at 53. Disposed between the side members Hand 48 are two bearing blocks 54 and =56, each of'whic'h is provided with channelsffor engagement with the shoulders 49- and "5 l' of the guide 50 so that the blocks may be moved .sure rolls 6 and "I.

7 Vertically. ,The upper block 54 is provided with an opening ,51 for-reception of the holder for the bearing for the roll 8, As shown in Fig. 19, this opening. 51 hasuppergand lower'boundaries of cylindrical configuration, Abearing holder 59 having cylindrical upper 'and lower faces is,

mounted in the opening 51. A needle bearing 58 is-mounted in an opening 55 in the holder 59. A cover plate 6I secured to the holder 59 by screws 60 serves to retain the bearing in place. The bearing 58 is provided with the usual packing andirotatably receives the neck or reduced portionL65 of the roll 8. Bythis means, the end of the roll 8'is mounted forfree rotation inthe bearing block 54L-The cylindricalmounting of the holder 59v permits tiltingof the roll and the bearing) with respect to the bearing block 54'. The lowerrbearing block .56 is of the same construction as the upperandneed not be described.

..The upperbearing block 54 is secured by a pin62to a piston .rod 63which is integral with a :piston'64 disposedinxthe pressure cylinder 66, the piston rod 63 extending through an opening 61 inthe top plate 52 f the frame 39. The cylinder 66 is bolted at .68 .to the top plate 52 and is provided at its upper end withfluid pressure supply ma'nsgenerally indicated at 69 and which will be described hereinafter. v

The'lower bearing block .56 is secured by a pin II to a threaded shaft I2 which threadably engages a rotatable nut 13 mounted in the base 44. As shown in Fig. 19,,this nut I3 is rotatably received in an opening 14 in the base 44 and is held against vertical movement with respect thereto by means of the upper flange I6 and a lower set collar 1], a thrust washer I8 being disposed betweenthe flange 16 and the top of the base 44. Secured to'the lower end of the nut I3 by means of a setscrew I9 isa bevel gear 8| meshing with asecond bevel gear 82 secured to the shaft 83 by means of a setscrew' 84. This shaft 83 is suitably mounted in bearings 86 in the base 31 and is provided at its outer end with a handwheel 42. A graduated collar85 is secured to the shaft 83 adjacent the handwheel 42. for cooperation with a-pointer 81 secured to the base 3I for indicating the extent of rotation of the shaft 83 and the vertical position of the roll 9.

r I'have described specifically the sideframe 39 of the roll unit 43 and the mounting therein of I 'beidescribed in detail. From the above, it isevident that the upper backing roll 8 ismoved vertically by means of the piston'rods 63 and that the lower backing roll' 9 is moved vertically by turning the-handwheel 42. The upper backing roll 8 is independently mounted in that either end may beadjusted. The lowerv backing roll 9 is not so mounted in that rotation of the handwheel 42 causes the bearing blocks at each end of the roll to move vertically at the, same rate. However, the lower roll may be independently adjusted by disconnecting the coupling of one bearing block to the shaft 83 as by loosening a setscrew 84,

Disposed between the rolls 8 and 9 are the pres- Referring now to Fig. 19, each end of each pressure roll is provided with a reduced portion or neck 88 for mounting in a bearing 89 carried by a bearing holder 9 I. These bearing holders 9I comprise flat blocks slidably received in a large bearing block 92 which is mounted for movement between theshoulders 49 and SI of the guide 5 0. The bearing block92 comprises fiat vertical side plates 90, held in spaced relation by the plates 93, which form short vertical guides for the bearing holders'9I.

A pair of springs 94 is disposed between the bearing holders 9| of the rolls 6 and I to' urge the rolls apart and into engagement with-the respective backing rolls. By this construction, the bearing holders 9I of the rollsfi and"! ,are slidable vertically. in the bearing block 92 which in turn is slidable vertically intheguide '50. I

The pressure supply unit 6-9 for the upper roll 8 will now be described. Referring now to Figs. 17 and 19, it will be seen that the upper end of the cylinders 66 and ID are closed by means of cylinder heads 95 and 96 welded thereto. Each head is provided with threaded openings9l,;98, and 99 for reception of fluid supply and discharge pipes. A hydraulic pump IUI is mounted on'a support IUZsecured to the upper end o'f the y1-" inder 66. This pump has a supply pipe I83 connected between the pump and a suitable reservoir of liquid such as oil. A-bifurcated-exitor pres: sure pipe I04 extends fromthe pump IIII and has its bifurcated ends threaded'into the openings of the cylinder heads 9 5 and 96, a valve I Ilfi being disposed in this line adjacent the pump, Abi furcated pipe III! has its bifurcated ends threaded into the openings 99 of the cylinder heads 95 and 96'and communicates through the valve I08 with a place of discharge which maybe the same reservoir to which the inlet I03 of thepump is connected. Another bifurcated pipe I69 is threaded into the openings 91; or the cylinder heads 95 and 96 and communicates through a valve III with a source of-air'or other gas under pressure, Disposed onthe lower side of each cylinder head 95 and 96 are pipes II2 and I I3 which thread into the threaded'openings 98 and 99, re-

' spectively, and serve to insure that the inlet and outlet of the liquid in the cylinders 66 and 18 will be below the liquid-level.

It is apparent from this description and from Figs. 16 and 19 that the pressure supply to the cylinder 66 on the right side of Fig. 19 is interconnected with that of the pressure'supply of the cylinder I0 on the other side of the machine so that the same pressure is applied tobothp'istons. Thus, from the respective valves I86, I98, and III, the pipes I04,JI81; and I09 are bifurcated. and connect both cylinders withthe same valves.

Each cylinder 66, Ill has a piston 64 which is providedon its upper side withv a clip-shaped gasket II4 securedtheretol by means of the plate H6 and bolts II! and on. its lower side with a rod 63 for attachment to the adjacent bearing block of the roll. 8.

L The bearing blocks 54 and on each end of the machine are provided with pointers I I9; see Fig. 17, for cooperation with a scale I2I secured 1 to-the sidemembers48 to'indicate the degree of spacing apart of the rolls. .These together with the graduated collar}? secured to thefshaftffl of the handwheel 42-serve as indicators of the positionof the rolls. T j

- Disposed atthe front'of the roll 'unit32 are vertical plates I22 and: I23, see Fig.' 19, which serve not only a entering guides for. insuring that a blank is, fed into the rolls at right angles ,thereto, but also as protecting guards for the v operator 'density of the article.

iustment of the spacing apart of the plates I22 and I23 to .accommodatevarious widths of articles .to be rolled.

. The operation of the device .will vnow be described. As an example, it will'be assumed that it .is desired .to bend a bimetallic article having a width of about 3%", a facing thickness of about 5., a backing thickness of about 5", and ajlength of about 12." to a cylindrical curvature about 12 in diameter. 'The operator will adjust the lower, backing roll 9' by means of the handwheel 42 so'that it is in an intermediate position substantially as shown in Fig. '19. He will then adjust the pressure applied to the upper roll so as to attain the required amount of mechanical working .of the article on passage through the rolls. In the specific example illustrated using pressure rolls 6 and I having a diameter of about 2" and cylinders 66 and lll having an inside diameter of 4", he will adjust the pressure in the cylinders, in a manner further described below, so that it is in the neighborhood of 700 pounds per square inch in the cylinders. He will then start the motor 33 to rotate the rolls and will pass the blank between the pressure rolls 6 and I. For the article in the example, the peripheral speed of the rolls should be about 12 feet per minute. Although it is possible to achieve the required bending in one pass through the rolls by using a high pressure, it is preferred that two or three passes will be required, much in the manner illustrated in Fig. 14. The indicated pressure is'such as to require several passes.

The use of several passes result in gradual bending "and in the complete elimination of cracking and chipping of the sintered facing.

This may be made clearer by the following description of the procedure to be followed bythe operator. 1

With each cylinder containing oil, to the level "shown in Fig. 17 and with all valves closed, the

operator will open air-supply valve I I I to admit air under pressure to the cylinder 66'. The pressure of this air will be relatively low or about 90 pounds'per square inch and is readily obtained.

I-Ie will then close the air supply valve I I I, open the-oil supply valve I06 and start the pump "II and allow it to continue pumping until a pressure'of about 700 pounds per square "inch is achieved in the cylinder 66. At this time',-he will close the oil supply valve I06 and stop the pump. The air in the cylinder 66 willbe compressed under a pressure of 700 pounds persquareinch and will exert this downward pressure on the piston 64 and through the piston rod 63'to the upper backing roll 8. Asa result of this, the pressure on the upper pressure roll 6 will be relatively constant regardless of the thickness of .the blank and. spacing apart of the .pressurerollsB and I. .Thefpresence of ,theair in the cylinders gives a cushioning efiect'and permits the pressurerolls to adjust for any differences in thickness and The provision for the supplyl' of oil under pressure is advantageous in that it permits the cushioning effect to be varied. By ,using a lower an adjustment of the level of the liquid in the oil level, more air will be trapped in the cylinder and the cushioning of the upper roll will be greater. By using a higher oil level, less air will be present and the cushioning effect on the roll will be less and a stifier action obtained. The oil is alsoadvantageous in that it is mechanically more feasible to obtain high oil pressures than it is to obtain high air pressures.

The use of gas under pressure through the valve I I I and pipe I09 is necessary only to permit cylinders 66 and 61. That is, pressure is necessary to force the liquid up the exhaust pipe H3 and out through the valve I08 to the reservoir.

If a discharge pump or siphon were provided to permit removal of the oil through the pipe II3, it would be sufiicient to merely have the valve I II communicate with atmospheric air,

While I have illustrated the use of an intermittently operated liquid'pump' IM and air supply 1 able compression spring could be substituted for each cylinder and its gas and oil supply.

Obviously, however, gas pressure alone could be employed. Thus, in Figs. 20, 21, and 22, I have illustrated .a modified form in which the pressure is obtained solely by means of gas pressure. This has some advantages in that the apparatus is simpler and oil leakages are no problem. To avoid the necessity for a source of high pressure air and to avoid leakages, the device comprises an air-operated diaphragm of large area.

Referring now to Fig. 20, I have illustrated the upper portion of the roll unit 32 as being of the same construction as the-unit shown in'Figs. 16 through 19; however, the upper plalte 52 and a pressure unit"69 of the embodiment of Fig. 17

have been substituted by the upper plate I36 which is likewise bolted at I31 to the roll unit 32. [The plate I36 carries on its upper side and secured thereto by means of the bolts I'3'I, a channel member I38. Sleeves I39 serve to space the channel I38'above the plate 136. Each end of the channel I38 has welded thereto a'vertical flat bar I 4I. An upper channel I42 joins the upper ends of the bars MI and is bolted thereto at I43. Disposed on the lower side of the upper channel I42 and weld-ed thereto at I44 is a circular backing plate I46. This backing plate, has a circular diaphragm I41 disposed on the lower side thereof and welded thereto at its peripheral margin I48. As isshown in Fig. 21, the backing from the air chamber through an opening I54'in the upper channel into a threaded opening 156 in the center of the backing plate I46. The chamber P52 is further connected at I51 through apr'essure-regulating valve l58'with apipeI'59 which is. connected to a suitable source of air under pressure. The pressure regulator I58 is of usual type and has a handle I60 for adjusting the pressure on its discharge side, a gauge I6I for indicating the line pressure in pipe I59. and a pressuregauge I62 for indicating the reduced the diaphragm I41.

. receive pressure. For bending the specific article used in illustration with regard to the apparatus shown pressure presentin'the chamber I52." The air valve for the other side member of the roll unit. A pressurer'elief valve I61, having an exhaust opening I68 and an adjustment nut I69, is connected to the diaphragm'by a pipe I64 threaded at I66 into the backing plate I46.

A drain pipe Ill and valve I12 are provided at the lower end of the chamber I52 to permit re- ..moval of condensed water and dirt from the chamber. r v v v It will be seen that'the described structure is such that the admission of air through the pipe I 3 between the backingplate I46 and the diaphragm I41 causes the latter to bulge downwardly under relatively great pressure due to the large area of the same. This downward pressure is imparted to the bearing block I13 by means of a rod I14 having a pressure plate I16 at the upper end thereof. The rod I14 is pinned at its lower end at I11 to the upper end of the bearing block I 13. The rod I14 extends upwardly from the bearing block I13 first through an opening I18 in-the plate I36 and then through an opening I19 in the lower channel member I38. The upper end of the rod I14 is provided with a head I8'I to which is welded the pressure plate I16. v

This pressure plate I16 is of rather large diameter and is disposed so as to receive the thrust from the diaphragm I41. The pressure plate I16 is also provided with a downwardly extending pin I82 which is slidably received in an opening I83 in the'lower channel I38 to restrain the plate I16 from rotation.

The opening I19 in the channel I38 through which the rod I1 4 extends has a threaded bushing I 84. This bushing I84 engages the lower side of the head I8I to limit downward movement of the pressure plate I16. The amount of vertical movement of the pressure plate I16 is obviously adjusted by turning the threaded bushing I84.

In the operation of the device the operator will turn the. handle I60 of pressure-regulating valve I58 to achieve the desired pressure in chamber I52 and between the backing plate I46 and This pressure will-serve to urge the diaphragm I41 downwardly, and it will in'turn force down the upper roll 8 through the medium of the pressure plate I16 and pressure rod I14. Due to the large area of the diaphragm, the downward pressure achieved will be of relatively great magnitude, although the pressure in the chamber I52 may be low. Thus, with an air pressure of about v50 pounds per square inch in the chamber I52 and with a pressure plate I16 of about 18Iin diametena total downward pressure of about 700 pounds is achieved. This is less than the theoretical pressure of .1270 pounds because of friction losses and the fact that the whole arjea of the pressure plate I16 does not the inFig-s. 16 to 19,, an air pressure 45 pounds per square inch has been used in the chamber I52.

The modified apparatus of Figs. to 22 can,

of course, be used with the jigs of Figs. 5 and 10.

.Both'modifications of apparatus may be utilized to form .fiat bimetallic blanks to a conical shape as shownin Figs. 10 and 11. To achieve this result thepressure by which the pressure rolls 6 and 1 are urged toward each other should be ofgradually. increasing amount from end to end of the rolls. This is readily achieved with the apparatus Figs. 20ftoj22 by adjusting the pressureregu- Thus. if it be desired ,to bend a bimetallic blank having a backing thickness of 1 6", a facing of a width of 3%". and an ,arcuate lengthof about 12" to aloonical shape having the large radius of 5% and a small radius of 55', the pressure applied to one diaphragm .will be about'45 pounds per squareinch and the pressure applied to the other will be about 55 pounds per square inch for pressure rolls having a diameter of about 2-'.

The apparatus of Figs. 16 to 19 has the two pressure cylinders interconnected and is thus not readily adapted to bend blanks to coneshape. However, it is obvious thatit could be adapted for this purpose by independently connecting the cylinders with the sources of gas'and air "under pressure so as to permit separate adjustment of the pressure in the cylinders. i

' While I have illustrated a machine having two pressure rolls and two backing rolls which are power driven and in turndrive the pressure rolls,

it is to be understood that other forms of apparatus may be utilized. Thus, it is possible to operate the machine with the pressure rolls removed. This can readily be accomplished by disassembling and removing the bearing blocks 92 for the pressure rolls and removing them and the rolls from the machine. Then. the backing rolls 8 and 9 can be used directly as pressure rolls. Similarly, while both rolls 8 and 9 are shown as power driven, it is obvious that only one need be so driven and that theother can be an idle roll.

This apparatus. forms the subject matter of divisional application s. N. 692,064 filed August 21,

' For some purposes, it may be'desirable to conto an elevated temperature. However, such procedure necessitates the provision of a protective atmosphere to prevent oxidation of the blank and is not necessary for most materials and conditions. For all practical purposes, the bending operation may be conducted with the blank at room temperature, and I have successfullybent articles having a facing thickness varying from %4:II 1/2,! I V V V In the above description, I have referred to the blank as having lateral and longitudinal dimensions and as being fed longitudinally between the pressure rolls or with its length disposed in the direction of movement. This has been done for purposes of illustration only, since the direction of bending is independent of the flat dimensions of the blank and is'controlled solely by the direction in which successive lateral areas are progressively mechanically worked.

clearly des cribe, the invention and it'is contemplated that there are numerous modifications and changes which may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In a method of bending a flat bimetallic article of the type having a more plastic facing bonded to a less plastic backing member to produce a curved article with the facing on its convex side and wherein the plasticity of the flat facing varies lengthwise of the article, the step of applying a substantially constant and yieldable pressure to the laterally extending areas of the facing of the fiat article successively and progressively along the length of the article, the applied pressure being of an intensity predetermined to effect a lengthening of the facing requisite to produce a desired curvature of the bimetallic structure.

2. A method of bending as claimed in claim 1 in which the facing of the article bent is composed of sintered metallic material.

SAMUEL K. WELLMAN.

14 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 165,819 Hahn July 20, 1875 347,271 Hunter Aug. 10, 1886 415,818 Miner Nov. 26, 1889 10 926,253 Hyde June 29, 1909 2,056,409 Ross Oct. 6, 1936 2,152,611 Swartz Mar. 28, 1939 2,174,635 Linderman Oct. 3, 1939 2,190,237 Koering Feb. 13, 1940 15 2,327,706 Halstead Aug. 24, 1943 2,446,891 Tower et al Aug. 10, 1948 2,446,892 Lowey Aug. 10, 1948 FOREIGN PATENTS 20 Number Country Date 11,283 Great Britain of 1894 

